Dull or roughened photographic film and process of making same



Patented July 22, I924.

UNED SATES tsaaaaa rarest QEFHCE.

RUDOLF OERTEL, OF LICHTERFELDE, NEAR BERLIN, AND FRIEDRICH DREYER, OFZEHLENDORF, NEAR BERLIN, GERMANY, ASSIGNORS TO THE FIRM GOERZPHOTOCHEMISCHE WERKE G. M. B. H., OF ZEHLENDORF, NEAR IBERIJ'N,GERMAKTY.

DULL 0R ROUGHENED PHOTOGRAPHIC FILM AND PROCESS OF MAKING- SAME.

No Drawing.

To all whom it may concern:

Be it known that we, Dr. RUDoLF OERTEL, chemist, a citizen of the GermanRepublic, and resident of Lichterfelde, near Berlin, Germany, andFRIEDRICH DREYER, superintendent, a citizen of the German Republic, andresident of Zehlendorf, near Berlin, Germany, have invented certain newand useful Improvements in Dull or Roughened Photographic Films andProcesses of Making Same (for which we have filed application in GermanyMarch 3rd, 1923) of which the following is a specification. p

This invention broadly refers to the manufacture of dulled or roughenedphotographic films such as used for the production of moving picturesand for similar purposes, and it is intended to devise new and improvedmeans for the production of such films and to generally improve andperfect the copying of films and of the pictures provided thereon.

In the procedure of copying photographic films for cinematographicpurposes there is the drawback that after the taking of but a smallnumber of copies very objectionable scratching of the negatives isproduced which greatly interferes with the quality of the copies, and inconsequencethereof the positive films, when projected, exhibit theinconvenience of cloudin or raining phenomena. The same draw ack occurslikewise with increasing scratching (f an originally unobjectionablepositive Attempts have already been made towards avoiding theseinconveniences by submitting the films, both positive as well asnegative films, to a dulling or roughening process; however, theordinary .methods of dulling or roughening by the employment .of a sandblast or by grinding fail to produce satisfactory results.

Now, in accordance with this invention the object of a dulling orroughening of the surface intended to dispense with the inconvenience ofthe clouding or raining of the projected picture is accomplished bysubmitting the surface to be treated to the application of a spray of adusting of varnish, japan or the like. This procedure may be effected byspraying the surface with a suitable transparent varnish, lacquer, japanor the like by means of a varnish Application filed December 26, 1923.Serial No. 682,827. l

' sprayer or injector, provision being preferably madeby' acorresponding selection of the nozzle section and of the pressure of theatomizing stream of compressed air, as well as by adjustment of theconcentration of the solution, to sov regulate the size of the particlesof varnish and the like that the desired fineness of grain for thedulling or roughening effect is obtained. The dullmg or rougheningproduced in this mannor is of such a degree of fineness that it .evenaffords the possibility of covering up begins to appear upon the copies.In certain cases it may also be of advantage to dull the crude negativefilm or the sheet of foil intended for the manufacture thereof, andparticularly, where the film is intended for the production of verydelicate negatives. It is also advisable to dull films with delicatenegatives before beginning to copy,

that is to say, before the occurrence of scratches, because the actionof the light in the luminous portions of the negative is therebydecreased. 1

The dulling or roughening is also of advantage in the case of positivefilms in case they exhibit such a degree of scratching that theprojected pictures show the well known phenomenon of clouding" orraining.

As a material for the lacquer or varnish to be sprayed a solution'of acellulose compound may preferably be used, such as for instance asolution of about one per cent (1%) nitro-cell'ulose in ether-alcohol1:1 which solution is sprayed by means of a varnish sprayer or injectorthe nozzle aperture of which is about a tenth millimeter,

coloring the film by adding a suitable pigment to the trans arentlacquer or the like. It is generally a visable to make an addition tothe lacquer or varnish of a metal salt soluble therein, of calciumchloride for example, in an amount of about one per cent of thepercentage of nitro-cellulose in the solution.

The invention has been described herein in its broad aspects, and itshould be understood that it is not limited to the particular substancesand means of procedure ashereinbefore stated merely for the purpose ofexplanation but it is susceptible of modifications and variations tosuit existing conditions and the convenience of the operator and withoutdeviating from the spirit of the invention as pointed out in the claims.

What we claim is 1. The process of dulling photographic sheets, whichconsists in treating the surface thereof with a spray of a varnishingcomposition..

2;The process of dulling photographic picture sheets, which consists industing the surface thereof with a solution of a cellulose derivative.

3. The process of dulling photographic picture sheets, which consists inspraying the surface thereof with a mixture of a var nishing compositionwith a metal salt soluble therein.

4. The process of dulling photographic picture sheets, which consists inspraying the surface thereof with a solution of nitrocellulose in etheralcohol averaging about one per cent of the substance.

5. The process of dulling photographic picture sheets, which consists inmaking a mixture of nitro-cellulose with a small amount of chloride ofcalcium, treating said mixture with ether alcohol and spraying saidmixture upon the surface to be treated.

6. The process of dulling photographic picture sheets, which consists inmixing nitro-cellulose with about one per cent of chloride of calcium,mixing about one per cent of said mixture with equal quantities of etherand alcohol, and dusting said mixture upon the surface to be treated.

7. As a new article of manufacture a photographic picture sheet carryinga dull coating consisting of finely subdivided transparent varnishingcomposition.

8. As a new article of manufacture a photographic picture sheet,carrying a dull coating of most finely'divided grains of a cellulosecompound.

9. As a new article of manufacture a photographic picture sheet,carrying a dull, most finely grained coating of a mixture of a cellulosecompound with a metal salt soluble in such compound.

10. As a new article of manufacture a photographic picture sheetcarrying a dull, most finely grained coating of a mixture of a cellulosecompound with approximately about one per cent of chloride of calcium.

In testimony whereof we have signed this specification in the presenceof a subscribe ing witness. v

DR. RUDOLF OERTEL. FRIEDRIOH DREYER. Witness:

E. HOLZERMAN.

